This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chronic H. pylori infection is the most important risk factor for gastric cancer, but the molecular and cellular mechanisms linking sustained H. pylori colonization with gastric carcinogenesis are poorly defined. We showed that chronic H. pylori infection of gastric epithelial cells leads to a state of apoptosis-resistance associated with decreased expression of p27 - a cyclin-dependent kinase inhibitor with tumor suppressor properties. This project examines the mechanisms by which H. pylori decreases p27 expression (aim 1), determines the functional consequences of p27 loss in gastric epithelial cells (aim 2) and explores other molecular changes in gastric epithelial cells accompanying their resistant to H. pylori-induced apoptosis, as candidate gastric cancer biomarkers (aim 3).